This invention relates to a method of operating an apparatus into which gases are introduced for purposes of, for example, leak detection or gas analysis. The gas to be examined by the apparatus is admitted thereto from one or more locations in one or several probe hoses which open into a chamber. The chamber is connected with the gas examining apparatus with the intermediary of a throttle and is further coupled to a vacuum pump or a delivery pump.
A gas examining apparatus of the above-outlined type which is provided with a sole probe hose is disclosed in German Offenlegungsschrift (Laid-Open Application) No. 2,441,124, to which corresponds British Pat. No. 1,489,953. The apparatus has the advantage that it has short periods of response and a high degree of sensitivity.
When working with gas examining apparatuses, such as leak detectors or gas analyzers, it is frequently necessary to use probe hoses of different lengths because often the apparatus, such as a leak detector, cannot be brought next to the container or the locations to be tested. For this reason, the gas examining apparatuses are, as a rule, marketed with a plurality of probe hoses of different lengths. It further may be necessary, for example, in case of testing several welds in the same operation, to simultaneously couple a plurality of probe hoses of identical or different lengths to the apparatus for a simultaneous examination of the gases flowing through the probes.
The use of conventional apparatuses of the above-outlined type involves the disadvantage that the results based on tests performed with probe hoses of different lengths or quantities cannot be compared with one another. Stated differently, if, for example, probe hoses of different lengths are used, identical leakage rates or gas concentrations which are in fact identical, are indicated by the apparatus as being different from one another. If now it is desired to obtain comparable measuring results with probe hoses of different lengths or different quantities, each time the hose arrangement is changed, it is necessary to recalibrate the apparatus, which is a time-consuming procedure.